Today I took my 997TT (BBI exhaust, ECU, pulley, IPD plenum, Sachs Stage II clutch and LWFW) out on a full load run. It was a hot day today in the OC and I had an adult passenger - which I normally don't have. The car got up to 5000 RPM in 5th gear and just stopped gaining power. Then when I took my foot off the gas I heard what sounded like rocks being thrown around in my engine. It happened for less than 1 second. My passenger - who knows a lot about cars - said that my engine was pinging and that I either needed to dial back my timing or use higher octane gas. He said that the higher octane gas would most likely stop it from happening.

I normally use 91 pump gas with a 20% infusion of race gas that bring the overall octane to about 108. This is what Betim at BBI instructed me to always do and I did for a year. But I stopped doing this about 4 months ago because it got expensive and I just got lazy. I use the 997TT as a DD and don't push it that hard very often.

After I dropped my friend off I drove it home pretty hard. The pinging did not happen again and the car appears to be running fine now. I never got a check engine light and the car did not seem to be running hot - at least not according to the gauges.

What are the chances that I damaged the engine? Do you guys agree that using the high octane gas infusion will correct the problem? This is the first time this has ever happened and I have had the car fully modded for a year now. I am almost in a panic state and don't want to drive the car now.

Just how concerned should I be? What is my best course of action?

 

Hi,

The dreaded rattle of a spray can from the engine bay, my TT Liberty was terrible for it on hot days.

Easiest fix would be to go the higher octane fuel. I used to use 98/100RON fuel - I can't remember how that fits in with the American MON system though. You mention ECU, is this a stock shelf map, or a custom tune? If it's custom, take it to the shop, they should be able to tune it out.

Cheers,
Nik

 

Your car is a ticking time bomb. You'd better give it to me and move on to a Ferrari 599.

 

I doubt that you damaged your engine in any way but this is interesting as I thought the engine computer automatically retards timing if knock (early detonation) is detected by the knock sensors. I am wondering though if your ECU upgrade or flash....has this function somehow off or deleted??

 

I think you can probably relax as long as it still runs smoothly with no knocks at idle.

I agree with your friend you probably experianced a little premature ignition in your engine. The knock sensor detected it and quickly pulled timing and boost to save your engine. The condition was probably exacerbated by the hot conditions outside.

If your tuner told you to run a mix of race gas it probably means he set the boost and timing aggressively. I would follow his directions. Alternatively, you could ask him to detune the car so it will safely run on 91 craptane. You can expect significant losses in performance if you go this route but that is a small price next to the cost of the engine.

 

Afraid so...

 

Hey Barrister.
I wouldnt worry at all, one small incident like that wont damage the engine at all. I suggest you talk to your tuner and either get him to detune it a bit or otherwise stick to adding the race gas into the mix.

 

Dana,

Have you considered having BBI adjust the ECU to work with 91 octane? I don't know much (OK, I know nothing) about mechanical issues like this, but every time I've heard a car ping it was related to fuel issues. If you're running 91 octane already, you've swallowed the related performance losses, and correcting the ECU would be more of a precautionary move. If I were in this position, I wouldn't feel comfortable running a fuel grade that wasn't what the car was tuned for, or recommended to use.

 

I have to take it on the chin for not using the race fuel that they gave me.

It's in my garage too. The car is faster and better with the race fuel but it is a PITA to use it sometimes.

I will just have to bite the bullet and use it on every fill up again.

Live and learn! Hopefully it won't turn out to be an expensive lesson.

 

How do you get 108 with 20% mix???